> ## Documentation Index
> Fetch the complete documentation index at: https://react-native-livechart.brandtnewlabs.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Line denoising

> Remove visually noisy path detail with a pixel tolerance while keeping the original chart data exact.

Dense or high-frequency samples can make a line look noisy even after the chart
has reduced overdraw to roughly pixel resolution. `line.simplify` applies a
shape-preserving simplification pass to the **rendered path**:

```tsx theme={null}
<LiveChart
  data={data}
  value={value}
  line={{ simplify: 1 }}
/>
```

The number is a screen-space tolerance in pixels. Intermediate points may be
removed when their deviation from the simplified path is no greater than that
tolerance. Endpoints remain fixed, and peaks or valleys larger than the tolerance
remain part of the path.

<Note>
  **Live example:**
  [`app/demo/line-denoising.tsx`](https://github.com/brandtnewlabs/react-native-livechart/blob/main/app/demo/line-denoising.tsx)
  shows the same deterministic signal raw and simplified, with live tolerance and
  curve controls.
</Note>

## What stays exact

Simplification changes only the line and area-fill geometry. It does not mutate
the `data` shared value, and the original points still drive:

* Y-axis range fitting and extrema
* the live value and dot
* markers anchored by time
* scrub interpolation and callback values
* threshold and reference-line calculations

This separation is useful when the chart should read more calmly without
changing the values a user can inspect or act on.

## Choosing a tolerance

Start with `0.75`–`1.5` pixels. That typically removes sub-pixel jitter while
leaving the recognizable signal unchanged.

| Value          | Effect                                                   |
| -------------- | -------------------------------------------------------- |
| `0` or omitted | Disabled; preserves the existing exact rendered path     |
| `0.75`         | Very subtle cleanup on dense or high-DPI charts          |
| `1`–`1.5`      | General-purpose denoising                                |
| `2`–`3`        | Stronger simplification; inspect narrow events carefully |

Because tolerance is measured after mapping values to the canvas, a setting has
a consistent visual meaning across datasets with very different value ranges.
Zooming or resizing naturally recalculates the path for the new screen geometry.

## Curve interpolation

`simplify` and `curve` control different stages. Simplification selects the
screen-space points to retain; `curve` then connects them with either the default
monotone cubic or straight segments:

```tsx theme={null}
<LiveChart
  data={data}
  value={value}
  line={{
    simplify: 1,
    curve: "linear",
    join: "round",
  }}
/>
```

Use the same tolerance when comparing curve styles: changing the curve does not
change the source data or the tolerance unit.

## Multi-series

Set the shared `line.simplify` to apply one tolerance to every series:

```tsx theme={null}
<LiveChartSeries series={series} line={{ simplify: 1 }} />
```

An individual `SeriesConfig` can override that value. Passing `0` opts a series
out while the other lines keep the shared setting:

```tsx theme={null}
const series = useSharedValue<SeriesConfig[]>([
  { id: "price", data: price, value: priceNow },
  { id: "benchmark", data: benchmark, value: benchmarkNow, simplify: 0 },
]);

<LiveChartSeries series={series} line={{ simplify: 1 }} />;
```

## Rendering cost

The pass runs on the UI thread after the chart's envelope-preserving dense-data
decimation. It reuses scratch buffers and processes bounded ranges anchored to
an absolute screen-pixel grid, so a moving live window does not repartition and
reshape retained history. This avoids new point-array allocation or unbounded
pathological scans on every frame.